机构地区:[1]中国地质大学(北京)水资源与环境学院,水利部地下水保护重点实验室(筹),北京100083 [2]北京市第四中学国际校区,北京100032
出 处:《岩矿测试》2023年第2期271-281,共11页Rock and Mineral Analysis
基 金:国家自然科学基金项目(42072275)。
摘 要:原位化学氧化(ISCO)修复技术由于修复周期短、效率高等特点已被广泛应用于土壤和地下水的有机污染修复。ISCO修复中所需的氧化剂的剂量通常用氧化剂需求量来衡量,在实际应用过程中,使用的氧化剂剂量过多或过少均会产生一定的负面影响。因此,氧化剂需求量的准确测算对于获得良好的工程修复效益具有重要意义。本文在对氧化剂需求量的组成及定义进行梳理、统一的基础上,重点综述了相关测算方法的原理和应用现状。ISCO修复中总氧化剂需求量(TOD)的组成包括污染物氧化剂需求量(POD)、天然氧化剂需求量(NOD)和氧化剂分解量(DEO)。NOD和DEO的存在为有机污染物有效的修复降解和TOD的准确测算带来了挑战。氧化剂需求量的测算方法可以分为实验法和化学计量模型法两大类,实验法又可以分为批实验法、柱实验法、注抽实验法和反应动力学模型法,批实验法的是目前应用目前较为最为广泛。在实验法中,同一样品的不同时间点获得的氧化剂需求量差距可以达到37%,因此应把污染物浓度在氧化作用下降低到目标限值所需要的时间作为氧化剂需求量的测定时间,并且为了更为精准地提供氧化剂需求量,有必要使用带有测试条件的表达方式来进行表示。目前的氧化剂需求量测算方法多针对于高锰酸钾氧化剂需求量。芬顿试剂和臭氧等分解性较强的氧化剂的DEO可能达到TOD的50%以上,现有方法对DEO的准确测算仍面临困难,应予以特别关注。除了需要开发出能够准确获得DEO的测算方法,场地施工条件对TOD的影响也需要进一步探究,氧化剂需求量的测算仍需一个更为科学的工作流程或指南。In-situ chemical oxidation(ISCO)refers to the use of appropriate conveyance technology to transport oxidants into soil or aquifer,where the contaminants are converted to low-or non-toxic substances by chemical oxidation.ISCO has been widely used for the remediation of organic contaminants in soil and groundwater due to its high efficiency and cost effectiveness.Oxidant demand is an important parameter in the application of ISCO.Once injected into the contaminated soil or aquifer,the oxidant reacts not only with the target contaminants,but also with natural organic matter(NOM)and reductive minerals(RM)such as Fe^(2+),Mn^(2+),S^(-)and S^(2-)in the medium.In addition,the oxidant may decompose naturally due to its own properties.If the amount of oxidant used is insufficient,the remediation of the contaminated site may not meet the project objectives and residual contaminants or reaction intermediates may be formed,resulting in a rebound of the contaminant concentration at the site.If too much oxidant is used,it would not only increase the cost of remediation,but also seriously damage the physical and chemical properties of soil,reducing the diversity of microbial communities.Therefore,accurate measurement of oxidant requirements is important to achieve good remediation performance.In previous studies,the specific meaning of terms related to oxidant demand is not consistent and they are often mixed in different studies,which would lead to ambiguity.In this review the composition and definition of oxidant demand is clarified and unified.The total oxidant demand(TOD)in ISCO is composed of pollutant oxidant demand(POD,the amount of oxidant consumed by oxidative degradation of pollutants),natural oxidant demand(NOD,the amount of oxidant consumed by natural organic matter and reducing minerals in soil or aquifer media),and decomposed oxidant(DEO,the amount of oxidant naturally decomposed due to its nature and the influence of environmental conditions).The methods for determining oxidant demand can be divided into two categ
关 键 词:原位化学氧化 氧化剂需求量 实验法 化学计量模型法
分 类 号:G264.3[历史地理—考古学及博物馆学] TQ031.7[化学工程]
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